NORTHERN
SAW-WHET OWL
Aegolius acadicus
The Northern Saw-whet Owl is highly nocturnal and migratory, making research of the species tricky, late-night business. These tiny owls fly south for the winter, usually in October: the Great Lakes are one of their favorite wintering regions. Interestingly, flying above the lakes does not scare this owl! Many have been reported flying over water, landing on ships, and even washing up dead on shore.
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Not all Northern Saw-whet Owls migrate south, however; some simply migrate to lesser latitudes for the winter. Adults tend to prefer mountain regions, while juveniles often flock to coastlines and migrate later in the season. Some of these owls remain in the northern boreal and hardwood forests year-round. Their favorite roosting trees include the Douglas Fir, Western Larch, and Western Red Cedar. These birds use large, dead trees, or snags, full of holes during the nesting season; old woodpecker and squirrel cavities make great nests. Their reliance on hardwood trees and snags makes the Northern Saw-whet Owl vulnerable to habitat deforestation and degradation.
Other threats include predation by larger raptors and nest raiders. Many large owls and hawks have been known to eat Northern Saw-whet Owls, and Red Squirrels sometimes raid nests, stealing eggs and hatchlings. If a nest is raided, or the eggs failed to hatch for another reason, the female may lay a new clutch of eggs that same year. During the nesting season, the female Northern Saw-whet Owl loses feathers along her keel (breastbone), leaving her skin exposed. This allows her bare skin to transmit heat more readily to the eggs, incubating them at a perfect temperature.
Nesting season is a busy time for both owl parents.The male must hunt strenuously to feed his growing family, and the female must incubate the eggs 24/7. For this reason, Northern Saw-whet Owls are normally monogamous, as are 90% of the world’s birds. It would be too exhausting for the male to feed two (or more!) nests at once. While nesting, Northern Saw-whet Owls are vulnerable to disturbances; loud noises, presence of humans, or predation may cause the female to abandon the nest.
The Northern Saw-whet Owl is commonly confused with its tiny relative, the Boreal Owl. However, you can distinguish the two species quite easily if you know what to look for. Northern Saw-whets lack a spotted forehead and tend to have a rusty-red tinge to their plumage. The Boreal Owl possesses a spotted forehead and appears mostly dark brown. Additionally, the Northern Saw-whet exhibits a black bill, while the Boreal has a yellowy-white bill.
If you live in North America, be sure to keep your eyes peeled and ears open for a Northern Saw-whet Owl the next time you are out on a forest adventure. This species covers nearly all of North America, but most people never even notice their presence.
Northern Saw-Whet juvenile
© Kurt Lindsay
© Kurt Lindsay
NORTHERN SAW-WHET OWL FACTS:
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A small reddish-brown owl with a large, round head, yellow eyes, black beak, and feathered feet
Males: head is warm brown with white spots on nape, belly is white with reddish streaks
Females: same as males
Young: less streaking; dark brown head and chest, reddish belly; conspicuous Y-shaped white marking above and between eyes
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OTHER NAMES: Saw-whet Owl, Queen Charlotte Owl
FAMILY: Strigidae
CLOSEST RELATIVE: Boreal Owl
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NORTHERN SAW-WHET SIZE:
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Females generally larger and heavier than males
Height: Males 17-21cm (6.7-8.3 in), Females 17-21cm (6.7-8.3 in)
Weight: Males 75g (2.6 oz), Females 100g (3.5 oz)
Wingspan Both: 46-56cm (18.1-22.0 in)
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NORTHERN SAW-WHET RANGE:
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Inhabits much of North America; from southeast Alaska and Queen Charlotte Islands in the west to Newfoundland in the east, south to Arizona and North Carolina; even found in mountainous regions in central Mexico
NORTHERN SAW-WHET HABITAT:
mostly coniferous forests; sometimes wooded riparian areas, swamps, and bogs
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NORTHERN SAW-WHET DIET:
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Mostly deer mice; commonly voles: sometimes small birds and insects
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NORTHERN SAW-WHET VOICE:
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Heard mostly during late breeding season
Males: a monotonous series of whistles, all on the same pitch; also a short series of “ksew-ksew-ksew” notes, often compared to the back and forth sound made when filing a saw
Females: softer and less consistent than males
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NORTHERN SAW-WHET NESTING:
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Nest Site: cavity nester; nests in holes made by woodpeckers; will also use nest boxes
Eggs: 5-7 eggs, laid asynchronously
Incubation: 27-29 days
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NORTHERN SAW-WHET HUNTING HABITS:
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Mostly nocturnal, occasionally diurnal; catches prey with feet and swallows in chunks, starting with the head
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NORTHERN SAW-WHET CONSERVATION STATUS:
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Not globally threatened
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NORTHERN SAW-WHET RESEARCH:
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Read about the Owl Research Institute's Northern Saw-Whet Owl study in RESEARCH.
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ALSO OF INTEREST:
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• Not the smallest owl in North America; the Elf Owl is
• Named for monotonous “saw-like” whistling occurring
primarily at night
• Females average 25% larger than males
• Have asymmetrical ear openings to allow sound
triangulation when hunting
• Size of individuals may increase with latitude increases
• Irruptions occur approximately every 4 years
• Fossils up to 500,000 years old found throughout the
United States
• Often pluck feathers from avian prey before consuming
• Eats small birds and mammals, beetles, and/or
grasshoppers
• Stores extra food on branches of inside the nest cavity
• Thaws frozen food through incubation before consuming
• Females choose nest sight
NORTHERN SAW-WHET OWL DISTRIBUTION IN NORTH AMERICA
Maps provided by The Birds of North America Online and the Cornell Lab of Ornithology.
ADDITIONAL INFORMATION:
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The Northern Saw-whet Owl ranges over much of North America, so your chances are good that one might live near you. Use your observation skills and see if you can track one down. Pay attention to the clues; first listen. Do you hear a repeated, monotonous whistle, especially at night in late winter or spring? Follow your ears to the next clue. Is the sound getting closer?
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Now look down, especially at the base of coniferous trees. Saw-whet owls leave lots of evidence beneath their favorite perching trees. All owls regurgitate the indigestible parts of their food, coughing up grayish pellets, filled with fur, feathers, and bones. And, like all animals, owls also defecate, leaving behind a spray of whitewash (otherwise known as bird doo-doo). When you find pellets and whitewash, you’ve hit the jackpot!
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Start looking up and see if you can spot a little reddish-brown owl peering back at you. Saw-whet owls are unique in allowing humans to come quite close before flying away. All of your detective work will pay off with the thrill of seeing the tiny Saw-whet Owl up close!
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